From 9f65e559c41af9ff4f628cbe3a364edd47fbb80a Mon Sep 17 00:00:00 2001
From: Eddie Kohler <ekohler@gmail.com>
Date: Thu, 19 Jul 2012 10:00:25 -0400
Subject: [PATCH] Configury: Check for C++11 rvalue references and template
 alias.

---
 config.h.in |  6 +++++
 configure   | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 m4/click.m4 | 16 ++++++++++++-
 3 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/config.h.in b/config.h.in
index e64b23d921..05d94a4a85 100644
--- a/config.h.in
+++ b/config.h.in
@@ -73,9 +73,15 @@
 /* Define if the C++ compiler understands #pragma interface. */
 #undef HAVE_CXX_PRAGMA_INTERFACE
 
+/* Define if the C++ compiler understands rvalue references. */
+#undef HAVE_CXX_RVALUE_REFERENCES
+
 /* Define if the C++ compiler understands static_assert. */
 #undef HAVE_CXX_STATIC_ASSERT
 
+/* Define if the C++ compiler understands template alias. */
+#undef HAVE_CXX_TEMPLATE_ALIAS
+
 /* Define if the machine is indifferent to alignment. */
 #undef HAVE_INDIFFERENT_ALIGNMENT
 
diff --git a/configure b/configure
index 307c772d25..aabe586f37 100755
--- a/configure
+++ b/configure
@@ -5317,6 +5317,38 @@ $as_echo "#define HAVE_CXX_CONSTEXPR 1" >>confdefs.h
 
     fi
 
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the C++ compiler understands rvalue references" >&5
+$as_echo_n "checking whether the C++ compiler understands rvalue references... " >&6; }
+if ${ac_cv_cxx_rvalue_references+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+int f(int &) { return 1; } int f(int &&) { return 0; }
+int
+main ()
+{
+return f(int());
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_cxx_rvalue_references=yes
+else
+  ac_cv_cxx_rvalue_references=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_cxx_rvalue_references" >&5
+$as_echo "$ac_cv_cxx_rvalue_references" >&6; }
+    if test "$ac_cv_cxx_rvalue_references" = yes; then
+
+$as_echo "#define HAVE_CXX_RVALUE_REFERENCES 1" >>confdefs.h
+
+    fi
+
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the C++ compiler understands static_assert" >&5
 $as_echo_n "checking whether the C++ compiler understands static_assert... " >&6; }
 if ${ac_cv_cxx_static_assert+:} false; then :
@@ -5349,6 +5381,38 @@ $as_echo "#define HAVE_CXX_STATIC_ASSERT 1" >>confdefs.h
 
     fi
 
+    { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the C++ compiler understands template alias" >&5
+$as_echo_n "checking whether the C++ compiler understands template alias... " >&6; }
+if ${ac_cv_cxx_template_alias+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+	cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+template <typename T> struct X { typedef T type; }; template <typename T> using Y = X<T>; int f(int x) { return x; }
+int
+main ()
+{
+return f(Y<int>::type());
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_cxx_template_alias=yes
+else
+  ac_cv_cxx_template_alias=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_cxx_template_alias" >&5
+$as_echo "$ac_cv_cxx_template_alias" >&6; }
+    if test "$ac_cv_cxx_template_alias" = yes; then
+
+$as_echo "#define HAVE_CXX_TEMPLATE_ALIAS 1" >>confdefs.h
+
+    fi
+
     { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the C++ compiler understands #pragma interface" >&5
 $as_echo_n "checking whether the C++ compiler understands #pragma interface... " >&6; }
 if ${ac_cv_cxx_pragma_interface+:} false; then :
@@ -7394,7 +7458,7 @@ else
 
 	    	    ac_cv_endian=0
 	    cat > conftest.$ac_ext <<EOF
-#line 7397 "configure"
+#line 7461 "configure"
 #include "confdefs.h"
 #include <$endian_hdr>
 #ifdef __BYTE_ORDER
diff --git a/m4/click.m4 b/m4/click.m4
index aedc08be9e..780ccd7faf 100644
--- a/m4/click.m4
+++ b/m4/click.m4
@@ -113,7 +113,7 @@ and Linux header files are GCC-specific.)
 	fi
     fi
 
-    dnl check for C++0x constexpr and static_assert
+    dnl check for C++11 features
 
     AC_CACHE_CHECK([whether the C++ compiler understands constexpr], [ac_cv_cxx_constexpr], [
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[constexpr int f(int x) { return x + 1; }]], [[]])],
@@ -122,6 +122,13 @@ and Linux header files are GCC-specific.)
 	AC_DEFINE([HAVE_CXX_CONSTEXPR], [1], [Define if the C++ compiler understands constexpr.])
     fi
 
+    AC_CACHE_CHECK([whether the C++ compiler understands rvalue references], [ac_cv_cxx_rvalue_references], [
+	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[int f(int &) { return 1; } int f(int &&) { return 0; }]], [[return f(int());]])],
+	    [ac_cv_cxx_rvalue_references=yes], [ac_cv_cxx_rvalue_references=no])])
+    if test "$ac_cv_cxx_rvalue_references" = yes; then
+	AC_DEFINE([HAVE_CXX_RVALUE_REFERENCES], [1], [Define if the C++ compiler understands rvalue references.])
+    fi
+
     AC_CACHE_CHECK([whether the C++ compiler understands static_assert], [ac_cv_cxx_static_assert], [
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[const int f = 2;]], [[static_assert(f == 2, "f should be 2");]])],
 	    [ac_cv_cxx_static_assert=yes], [ac_cv_cxx_static_assert=no])])
@@ -129,6 +136,13 @@ and Linux header files are GCC-specific.)
 	AC_DEFINE([HAVE_CXX_STATIC_ASSERT], [1], [Define if the C++ compiler understands static_assert.])
     fi
 
+    AC_CACHE_CHECK([whether the C++ compiler understands template alias], [ac_cv_cxx_template_alias], [
+	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[template <typename T> struct X { typedef T type; }; template <typename T> using Y = X<T>; int f(int x) { return x; }]], [[return f(Y<int>::type());]])],
+	    [ac_cv_cxx_template_alias=yes], [ac_cv_cxx_template_alias=no])])
+    if test "$ac_cv_cxx_template_alias" = yes; then
+	AC_DEFINE([HAVE_CXX_TEMPLATE_ALIAS], [1], [Define if the C++ compiler understands template alias.])
+    fi
+
     AC_CACHE_CHECK([[whether the C++ compiler understands #pragma interface]], [ac_cv_cxx_pragma_interface], [
 	save_cxxflags="$CXXFLAGS"; CXXFLAGS="$CXXFLAGS -Werror -Wall -W"
 	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#pragma interface "foo.c"